Re: [PATCH] tls: don't abort the connection on signal-interrupted sends

On Thu, 2026-07-23 at 09:26 -0700, Jakub Kicinski wrote:

On Mon, 20 Jul 2026 11:08:47 +0200 Maximilian Immanuel Brandtner
wrote:

quoted

When a signal interrupts a blocking send, tls_tx_records() treats
the
resulting -ERESTARTSYS as a transmission failure and marks the
socket
errored via tls_err_abort() with the raw error code. Later syscalls
return the kernel-internal errno 512 (ERESTARTSYS) to userspace, as
the
signal it stems from is no longer pending during syscall exit and
thus
never translated.

Can we just add ERESTARTSYS handling? I never heard of the other
codes
you're checking TBH, can they actually surface?

I don't know whether three are any drivers that call these error codes
in practice. However, I know that these other errnos also get handled,
by the signal re-entrancy logic (for example see `handle_signal()` in
`arch/x86/kernel/signal.c`). I think all these error codes should
propagate to the relevant signal logic to be converted to the right
error code and avoid leaking kernel-internal error codes to user-space.

Maybe EINTR could be removed from the patch. I just kept it in just in
case.

quoted

An interrupted send is not a connection error: the partially sent
record
stays queued and is resent later. Interrupt error codes are
therefore
excluded from the abort in the same way as -EAGAIN.

Fixes: b341ca51d267 ("tls: Fix tls_sw_sendmsg error handling")
Signed-off-by: Maximilian Immanuel Brandtner <redacted>
---
Tested on top of net commit 3f1f75536668 ("net: openvswitch: reject
oversized nested action attrs").

Several subsystems contain static helper functions to classify
these
interrupt errnos. It might be worthwhile to refactor these static
functions into a generic helper function.

Yes, please.

I'll prepare a seperate patch-set for that then. Note this helper will
only cover `ERESTARTSYS`, `ERESTARTNOINTR`, `ERESTARTNOHAND`, and
`ERESTART_RESTARTBLOCK`, because there are a bunch of places in the
kernel where these 4 error codes in particular are checked against.

quoted

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index d4afc90fd796..3c9e94069e82 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c

@@ -405,6 +405,24 @@ static void tls_free_open_rec(struct sock *sk)

 	}
 }
 
+static bool tls_is_non_restartable_err(int err)
+{
+	if (err >= 0)
+		return false;

This doesn't belong in a helper for classifying errors.

So you would prefer if (rc < 0 && !tls_is_restartable_err(rc))

quoted

+	switch (err) {
+	case -EAGAIN:
+	case -EINTR:
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+	case -ERESTART_RESTARTBLOCK:
+		return false;
+	default:
+		return true;
+	}
+}
+
 int tls_tx_records(struct sock *sk, int flags)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);

@@ -458,7 +476,7 @@ int tls_tx_records(struct sock *sk, int flags)

 	}
 
 tx_err:
-	if (rc < 0 && rc != -EAGAIN)
+	if (tls_is_non_restartable_err(rc))
 		tls_err_abort(sk, rc);
 
 	return rc;